// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_BUILTINS_CONSTANTS_TABLE_BUILDER_H_
#define V8_BUILTINS_CONSTANTS_TABLE_BUILDER_H_

#include "src/allocation.h"
#include "src/base/macros.h"
#include "src/handles.h"
#include "src/identity-map.h"

namespace v8 {
namespace internal {

    class Isolate;
    class Object;

    // Utility class to build the builtins constants table and store it on the root
    // list. The constants table contains constants used by builtins, and is there
    // to avoid directly embedding them into code objects, which would not be
    // possible for off-heap (and thus immutable) code objects.
    class BuiltinsConstantsTableBuilder final {
    public:
        explicit BuiltinsConstantsTableBuilder(Isolate* isolate);

        // Returns the index within the builtins constants table for the given
        // object, possibly adding the object to the table. Objects are deduplicated.
        uint32_t AddObject(Handle<Object> object);

        // Self-references during code generation start out by referencing a handle
        // with a temporary dummy object. Once the final Code object exists, such
        // entries in the constants map must be patched up.
        void PatchSelfReference(Handle<Object> self_reference,
            Handle<Code> code_object);

        // Should be called after all affected code (e.g. builtins and bytecode
        // handlers) has been generated.
        void Finalize();

    private:
        Isolate* isolate_;

        // Maps objects to corresponding indices within the constants list.
        typedef IdentityMap<uint32_t, FreeStoreAllocationPolicy> ConstantsMap;
        ConstantsMap map_;

        DISALLOW_COPY_AND_ASSIGN(BuiltinsConstantsTableBuilder);
    };

} // namespace internal
} // namespace v8

#endif // V8_BUILTINS_CONSTANTS_TABLE_BUILDER_H_
